A superabsorbent polymer, in general refers to a water-swellable, water-insoluble polymer, or material, capable of absorbing at least about 10 times its weight, and up to about 30 times or more its weight in an aqueous solution containing 0.9 weight percent sodium chloride solution in water. Examples of superabsorbent polymer may include a crosslinked partially neutralized acrylate polymer, and the formation of superabsorbent hydrogel from the polymerization, and formation of particulate superabsorbent polymer compositions capable of retaining the aqueous liquids under a certain pressure in accordance with the general definition of superabsorbent polymer.
The superabsorbent polymer hydrogel can be formed into particles, generally referred to as particulate superabsorbent polymer, wherein the particulate superabsorbent polymer may be surface-treated with surface crosslinking, and other surface treatment and post treated after surface crosslinking to form particulate superabsorbent polymer compositions. The acronym SAP may be used in place of superabsorbent polymer, superabsorbent polymer composition, particulate superabsorbent polymer compositions, or variations thereof. Commercial particulate superabsorbent polymer compositions are widely used in a variety of personal care products, such as infant diapers, child training pants, adult incontinence products, feminine care products, and the like. In general, these particulate superabsorbent polymer compositions have a centrifuge retention capacity (CRC) of at least 25 grams of 0.9 weight percent sodium chloride aqueous solution per gram of the polymer. Particulate superabsorbent polymer compositions are also designed to quickly uptake bodily fluids, which requires a reasonable absorption speed, and are designed to quickly distribute fluids in high concentrations, which requires high permeability, which can be measured as high gel bed permeability (GBP). Commercial particulate superabsorbent polymer compositions undergo significant processing during manufacturing and converting processes, resulting in lack of stability of the original gel bed permeability. This lack of stability or reduction of the value of various properties, including gel bed permeability may be one of the causes of premature leakage and skin wetness problems for absorbent articles.
There is thus a need or desire for particulate superabsorbent polymer compositions that can withstand absorbent product manufacturing and converting processes without resulting in a significant reduction in properties. There is a further need or desire for a method of increasing the permeability stability of a particulate superabsorbent polymer composition.